1. Field of the Invention
This invention relates to a connector device for a transmission body for coupling two members which rotate relative to each other through a limited number of revolutions.
2. Description of the Related Art
For example, the prior art connector device shown in FIG. 1 is used with the steering device of a car. The connector device is used in a transmission body for transmitting an electric signal, light signal or electric power between a fixed member and a rotation member which rotates relative to the fixed member within a limited number of revolutions.
In the connector device, a fixed housing 1 and a movable housing 2 are rotatably combined with each other to create a ring-form space, and a flexible flat cable 3 is received in the ring-form space. The flat cable 3 is fixed at one end on an external cylindrical portion 1a of the fixed housing 1 and fixed at the other end on an internal cylindrical shaft portion 2a of the movable housing 2 which serves as a rotation shaft. Further, the flat cable 3 is loosely wound in a spiral form with a preset clearance C.sub.1 between it and the inner wall of a flange portion 2b of the movable housing 2. With this construction, the housings 1 and 2 can be rotated relative to each other through a plurality of revolutions depending on (the ceiling and uncoiling) the tightening and loosening of the flat cable 3.
With the above connector device, since the flat cable 3 is loosely wound in the housings 1 and 2, the flat cable 3 is permitted to move not only in a radial direction with respect to the internal cylindrical shaft portion 2a but also in an axial direction along the internal cylindrical shaft portion 2a by a distance of the clearance C.sub.1. Therefore, the flat cable 3 received in the housings 1 and 2 vibrates when the car is running, and it strikes the inner wall to generate an unpleasant impact or collision noise which is so-called "bouncing noise". In particular, since the speed at which the flat cable 3 collides against the inner wall increases as the clearance C.sub.1 is made larger, the unpleasant bouncing noise becomes larger when the clearance C.sub.1 is made larger.
In order to solve the above problem, for example, a connector device such as an electrical connection device shown in FIG. 2 has been proposed in which a flat cable 7 is received in housings which are respectively formed of a movable member 5 and a fixed member 6 and constructed to be freely rotated relative to each other and a resilient member having a projection arm 8a which serves to press the flat cable 7 against one of the movable member 5 and fixed member 6 is provided (Japanese Utility Model No. 62-124785; U.S. Pat. No. 4,744,763).
With the above prior art electrical connection device, generation of the unpleasant bouncing noise described above can be suppressed. It is, however, extremely difficult from an economical viewpoint to mass-produce the devices such that all of the products have a dimension precision high enough to always provide an adequate force of pressing the flat cable 7 against the movable member 5 or fixed member 6 under any operating conditions, in consideration of the manufacturing cost.
If sufficient dimensional precision is not attained and the flat cable 7 is applied with an excessively large force by the resilient member 8, smooth loosening and tightening of the cable are hindered, causing serious troubles such as a reversing of the flat cable 7 near the ends thereof at which it is fixed to the movable member 5 and the fixed member 6. This may result in disconnection of the conductive member in the flat cable, or an increased torque required for operation (SAE Paper 892010).